The present invention generally relates to DC to DC converters, also known as inverters, and more particularly to a resonant switching converter in which switching power devices are turned on and off at zero current, resulting in great reductions in switching losses at any power handling level.
The efficiency, frequency and miniaturization of conventional DC to DC converters is limited mainly by switching losses. The switches employed in these circuits typically open and close with high currents, resulting in high power transients that stress the switches and cause power losses and high electromagnetic interference. The switching losses for a 500 watt converter, operating at 10 KHz and using the best conventional techniques, can be as high as 40 watts. This dissipation occurs in short transients with peaks to 4 kilowatts. The voltages and currents have extremely high frequency components due to spiked or square waveshapes. Besides electromagnetic interference problems, these high frequency components cause additional power losses or reduced reliability in magnetic devices, in filter capacitors, and in the reverse recovery of diodes. Moreover, the weight devoted to electromagnetic interference shielding can be considerable.